Also Known As: Dual Drain, Main Drain, Sump
Gravity can cause dangerous suction at these points, elevating the risk of entrapment, which can cause serious injury or death. The Virginia Graeme Baker Safety Act was signed into law in 2007 as a way to address this risk. Among other things, this regulation requires that main drains be covered with grates or antivortex covers, which divert the flow of water.
On the other hand, skimmers suck water from the surface of the pool. These drains are designed to pull water through the filtering system. A skimmer basket catches larger debris, like leaves, while smaller particles are caught in the pools filtering system. Although these drains do require suction, in a properly built and functioning pool, there is virtually no danger of injury from these drains. More than one open drain balances the force of the suction throughout the pool.
In addition, a pool may be outfitted with vacuum ports or drains, which may be driven by the pool pump or a separate pump. Vacuum hoses are attached to these ports, allowing the pool surface to be vacuumed or scrubbed with specially designed tools. The water is sucked into the vacuum ports and filtered through the pools filtering system.